Test: fee.url option in LND

A serverless function project for testing the fee.url option in LND.
The functions are deployed on Vercel: https://test-lnd-fee-url.vercel.app.

APIs

• /api/mempool-fees: Mapping fee rates from mempool API:

  • fee_by_block_target[3]: fastestFee
  • fee_by_block_target[6]: halfHourFee
  • fee_by_block_target[8]: hourFee
  • fee_by_block_target[10]: economyFee
  • min_relay_feerate: minimumFee

• /api/mempool-hill-fees: Mapping fee rates from mempool API, it aims to lower the commit_fee as low as possible, regardless of the actual mempool fee rates, when force-close happens, the participant can bump the transaction with a CPFP transaction:

  • fee_by_block_target[3]: 1012
  • fee_by_block_target[4]: fastestFee
  • fee_by_block_target[6]: halfHourFee
  • fee_by_block_target[8]: hourFee
  • fee_by_block_target[10]: economyFee
  • min_relay_feerate: 1012

• /api/mempool-min-fees: Mapping only the minimalFee from mempool API, it aims to give the commitment transaction a minimal chance to be pushed in the mempool:

  • fee_by_block_target[3]: minimumFee
  • min_relay_feerate: minimumFee

• /api/mempool-min-hill-fees: Mapping fee rates from mempool API, it aims to provide a balance that the commit fee is not too low by using the economyFee as the commit fee rate, allowing force-close transactions to be stayed in the mempool without being purged immediately:

  • fee_by_block_target[3]: economyFee
  • fee_by_block_target[4]: fastestFee
  • fee_by_block_target[6]: halfHourFee
  • fee_by_block_target[8]: hourFee
  • fee_by_block_target[10]: economyFee
  • min_relay_feerate: minimumFee

• /api/mempool-custom-hill-fees: Mapping fee rates from mempool API, it works exactly like the mempool-min-hill-fees by default, but you can pass maxCommitFeeRate to the querystring to limit the maximum commit fee rate:

  • fee_by_block_target[3]: min(economyFee, query.maxCommitFeeRate)
  • fee_by_block_target[4]: fastestFee
  • fee_by_block_target[6]: halfHourFee
  • fee_by_block_target[8]: hourFee
  • fee_by_block_target[10]: economyFee
  • min_relay_feerate: min(minimumFee, query.maxCommitFeeRate)

• /api/static-min-fees: All fee rates are fixed to 1012:

  • fee_by_block_target[3]: 1012
  • min_relay_feerate: 1012

Apply fees

To apply the fee.url option in LND, you can edit your lnd.conf file and add the following line, then restart your LND node, the option should be applied in a random timeout:

fee.url=https://test-lnd-fee-url.vercel.app/api/mempool-fees

Self-hosting

The project is open-source, and you can self-host it as serverless functions.

Or you can clone the project and deploy it on Vercel.